Method of improving the carrier precipitation of plutonium



METHOD OF MPROVING THE CARRIER PREKIIPHTATI'ON @F PLUTONIUM Application February 3, 1945, Serial No. 576,127

11 Claims. (Cl. 23-145) This invention relates to a procedure for the processing of materials containing the element of atomic number 94, known as plutonium, for separating the plutonium from extraneous matter such as substances of the kind present in neutron irradiated uranium exemplified by uranium and especially fission products, and the like radioactive contaminants. More particularly, this invention concerns a separatory and concentration procedure involving the use of a fluoride type of carrier wherein certain improved procedure is employed in forming the carrier.

As described herein, the isotope of element 94 having a mass of 239 is referred to as 94 and is also called plutonium, symbol Pu. In addition, the isotope of element 93 having a mass of 239 is referred to as 93 Reference herein to any of the elements is to be understood as denoting the element generically, whether in its free state or in the form of a compound, unless indicated otherwise by the context.

Elements 93 and 94 may be obtained from uranium by various processes which do not form a part of the present invention including irradiation of uranium with neutrons from any suitable neutron source, but preferably the neutrons used are obtained from a chain reaction of neutrons with uranium.

Naturally occurring uranium contains a major portion of U a minor portion of U and small amounts of other substances such as UX and UX When a mass of such uranium is subjected to neutron irradiation, particularly with neutrons of resonance or thermal energies, U by capture of a neutron becomes U which has a half life of about 23 minutes and by beta decay becomes 93 The 93 has a half life of about 2.3 days and by beta decay becomes 94 Thus, neutron irradiated uranium contains both 93 and 94 but by storing such irradiated uranium for a suitable period of time, the 93 is converted almost entirely to 94 In addition to the above-mentioned reaction, the reaction of neutrons with fissionable nuclei such as the nucleus of U results in the production of a large number of radioactive fission products. As it is undesirable to produce a large concentration of these fission products which must, in view of their high radioactivity, be separated from the 94 and further as the weight of radioactive fission products present in neutron irradiated uranium is proportional to the the amounts of 93 and 94 formed therein, it is preferable to discontinue the irradiation of the uranium by neutrons when the combined amount of 93 and 94 is equal to approximately 0.02 percent by weight of the uranium mass. At this concentration of these substances, the concentration of fission elements which must be removed is approximately the same percentage.

A number of processes have already been proposed for accomplishing the separation and concentration of Pu. Certain of these processes are generically known as the bismuth phosphate type process and the wet fluoride type of process. These processes are the invention of others and the details of the processes are described in copending applications as for example app. Ser. No. 519,714 to be referred to hereinafter, which gives details relative to such processes. Consequently, all of the details of operation of the aforementioned processes are not described herein.

In some instances, it has been customary to utilize in the same separation and recovery process both the bismuth phosphate treatment and lanthanum fluoride treatment. Consequently, the bismuth phosphate treatment is referred to herein to some extent for background although the present invention is concerned particularly with the formation of fluoride type of carrier precipitates. That is, the present invention in its preferred em bodiment concerns the formation of the fluoride type of precipitates exemplified by a lanthanum fluoride precipitate carrying Pu. In processes of the aforementioned type, either combination processes where several different types of carriers are used, including the formation of a fluoride precipitate, or processes where fluoride compounds are more or less directly pecipitated, the formation of easily separable fluoride compounds carrying Pu or fission products or comprising a fluoride compound of Pu may present certain difficulties. For example, one carrier precipitate commonly formed is lanthanum fluoride. This precipitate has been formed under acid comditions by adding to the acid solution a source of fluoride ions and a source of lanthanum ions. The characteristics of the precipitates formed under acid conditions are such as to present some difiiculty of separation because of the finely divided nature and dispersion thereof. That is; it-may be required to centrifuge these precipitates at relatively high speeds for extended periods or to employ a special filtration technique for separation from the surrounding liquid.

In accordance with the present invention, it has been found that a precipitate of better characteristic may be formed provided the formation of the precipitate is caused to take place in the presence of certain inorganic compounds.

The meaning of the terms bismuth phosphate type of process, fluoride type of process, preformed and coformed precipitates, product and by-product precipitate and similar terms will be apparent as the description proceeds.

This invention has for one object, to provide improvements in a method for the separation and recovery of plutonium.

Another object is to provide a method of separating plutonium by procedure wherein certain additions supplemental to those heretofore used are employed.

Another object is to provide improved procedure for forming more easily separable precipitates.

Still another object is to provide a new procedure particularly useful in forming a fluoride carrier precipitate containing Pu.

Another object is to provide a new procedure for forming byproduct fluoride carrier precipitates.

Still another object is to provide a procedure for Patented Dec. 9, 1958- traneous materials may be separated and concentrated by the use of a series of steps involving the formation of certain carrier precipitate type of treatments. These treatments may be similar to known practice as respects certain of the additions, temperatures and similar features. However, we have found that the formation and character of such carrier precipitates may be improved by forming such precipitates in the presence of certain inorganic compounds as set forth in detail hereinafter. By the formation of the carrier precipitate under such conditions, not only are the advantages previously obtained in the processes still obtainable, but advantages such as the formation of a mixed precipitate having improved characteristics are obtained. 7

An illustration of the types of carrier precipitates involved are described in app. SerialNo. 519,714, filed January'26, 1944, now Patent No. 2,785,951, Thompson and Seaborg, and reference is made to that application for further'disclosure, details thereof being omitted from the present disclosure except where necessary to an understanding of the present invention. As set forth in said application, it has been discovered that plutonium has more than one oxidation state, including a lower oxidation state or states referred to herein as Pu in which the element is characterized by forming insoluble phosphates and fluorides and a higher oxidation state or states referred to as Pu in which the element forms soluble phosphates and fluorides.

In accordance with the present invention, for example, a fluoride carrier precipitate is coprecipitated in a certain manner with inorganic materials whereby the characteristics of the resultant fluoride mixed precipitates are improved.

The solutions containing Pu which may be treated by out invention are the same type of solutions as heretofore treated. One common type of solution containing Pu subject to separation and recovery procedure is the solution initially processed by a bismuth phosphate type of treatment. This type of solution and its treatment are described in detail in application 519,714 aforementioned. Such solutions comprise a nitric acid containing liquid having a content of Pu therein. The nitric acid solution may also contain other materials such as a content of phosphoric acid. The solution may also contain certain extraneous matter such as radioactive materials which the subsequently applied fluoride precipitation treatments may eliminate or reduce. As referred to above, by means of a fluoride precipitation treatment applied to the solution containing the Pu in the (r) condition, the resultant fluoride precipitate (product precipitate) carries the Pu away from extraneous matter. By means of a fluoride precipitation applied to the solution having the Pu state (by-product precipitate), extraneous matter is carried away by the fluoride precipitate leaving the Pu in the supernatant liquid from this precipitation.

In either instance, by means of our inventi0n,'the char- I acteristics of the fluoride precipitate formed may be improved and a precipitate which is more easily separable and otherwise has better characteristics may be obtained.

Broadly, therefore, our invention may be applied to various solutions. The solutions to be processed by our invention have added thereto such inorganic reagents in accordance with this invention as may be required, de-

pendent upon the particular composition and condition process of treating the lanthanum fluoride carrying Pu to recover the Pu therefrom.

A general illustration of the coprecipitation with an inorganic material is as follows: A solution containing Pu is reduced in any conventional manner, as with oxalic acid, and a content of fluoride ion incorporated therein such as by the addition of hydrogen fluoride to the solution. There is then added to the solution an inorganic material such as lead nitrate. The solution is then treated with a mixture of lanthanum nitrate and sulfuric acid which causes a mixed precipitate of lanthanum fluoride and lead sulfate to be thrown down. There are variations in the method of addition as will be described hereinafter.

The resultant mixed lanthanum fluoride precipitate may be more readily centrifuged out of the liquid containing it, and the Pu is more completely removed.

A still further understanding of my invention may be had by reference to the following detailed examples. In these examples the solution containing Pu which was treatedwas the same in each instance. Thatis, the solution corresponded to a solution from standard processing and was approximately 1 normal in nitric acid. The solution also contained a content of oxalic acid (H C O amounting to about 0.05 M and phosphoric acid (H PO to the extent of 0.1 M.

The methods of treating solutions for forming the lanthanum fluoride precipitates may vary. That is, a coformed precipitate may be prepared by dispersing lanthanum ions throughout the solution after which the source of fluoride ion is added. By this procedure the precipitate forms substantially throughout the solution.

A preformed precipitate is obtained by reverse procedure. That is, the solution is supplied with source of fluoride ions, as for example by incorporating excess hydrogen fluoride. Then a source of lanthanum ions is added, as for example by supplying lanthanum nitrate to the solution. In this instance the lanthanum fluoride precipitate forms on or near the surface. Hence, agitation and digestion are employed to distribute the carrier precipitate throughout the solution.

Therefore, the character of the fluoride precipitates may individually vary somewhat dependent upon whether they are coformed or preformed. Also a preformed precipitate may exhibit somewhat better characteristics as far as separability than the coformed precipitate. However, it has been found that by the application of our invention to any type of lanthanurn fiuoride formation or other fluoride precipitates that the'precipitates resulting from processing in accordance with our invention are distinctly superior in certain respects to the lanthanum fluoride precipitate formed in a conventional manner.

A further understanding of our invention Will be had from a consideration of the examples which follow. Also an appreciation of the improvement obtainable will be observed by reference to the attached drawing wherein certain curves have been shown which drawing forms a part of the present application and will be referred to in detail hereinafter.

The first two examples set forth, namely Examples I and H, are control runs. That is, the procedure set forth therein does not embody our invention but merely constitutes more or less standard operation. These runs are described for furnishing background and data from which a comparison may be made for observing the effects obtainable by application of our invention.

Examples Ill and EV are similar to the aforementioned tworuns with the exception that in these examples procedures in accordance with the present invention have been included.

in all of these examples the process was carried out in 208 ml. stainless steel containers with mechanical aeitation. The temperature of the operation was room temperature. The period of digesting the precipitate about 2 /2 hours after all the reagents had been added. After the period of digestion the liquid containing precipitate was poured into 100 ml. conical containers for observing the settling rates. An improved settling rate 1s in itself an improved characteristic. Also some indication of whether improved centrifuging will be obtamed may be noted from the settling rate. In some examples, centrifuging tests were employed to determine centrifuging improvement imparted by our invention.

Example I In this example for the purposes of control, a coformed lanthanum precipitate was prepared. Approximately 90 ml. of the solution in which the lanthanum fluoride precipitate was to be formed was placed in a stainless steel container. There was then added 9 ml. of a lanthanum nitrate solution containing approximately 2.5 milligrams of lanthanum per milliliter. Then 0.74 ml. of concentrated hydrogen fluoride was added at the rate of about 3 drops, per each two minute interval, until 45 drops had been incorporated. The concentrated HF used about 27 N. However, other strengths may be employed if desired. The precipitate which formed was digested as described above. After digestion, the liquid containing precipitate was poured into a container as above described for observing the settling rate. The results of the observations were recorded as will be described when reference is made to the attached drawing.

Example II In accordance with this example, another control was prepared but in this instance the lanthanum fluoride carrier precipitate was preformed. That is, approximately 87.3 ml. of nitric acid solution in which the lanthanum fluoride precipitate was to be formed was placed in a stainless steel container. Approximately 3.7 ml. of concentrated hydrogen fluoride was incorporated. Thereafter there was added 9 ml. of lanthanum of a concentration of 2.5 milligrams per milliliter, namely the same type of solution as used in the preceding example. This was added at the rate of approximately 5 drops, per minute interval, until 150 drops had been incorporated. Agitation and digestion were applied. Thereafter the liquid containing precipitate was transferred to a container for observing its settling rate and the data resulting from the observation plotted as will be described when reference is made to the drawing.

Example III In accordance with this example the process was carried out substantially similar to the preceding examples but in addition an inorganic material was coprecipitated with the lanthanum fluoride. In further detail, approximately 83.5 ml. of nitric acid solution in which the lanthanum fluoride precipitate was to be formed were placed in a stainless steel container. About 3.7 ml. of concentrated hydrogen fluoride was incorporated into the solution. There was also incorporated 2.5 ml. of a 4 N sulfuric acid solution for furnishing a source of sulfate radical. There was then added 10.32 ml. of a mixture comprising a source of both lanthanum ions and lead ions. This mixture comprises 6.6 ml. of 10% lead nitrate solution and 4-5 ml. of lanthanum nitrate solution of a concentration of 2.5 milligrams of lanthanum (of a +3 valence) per milliliter. This mixture addition was made at the rate of about 0.5 ml. for each 1 /2 minute interval. After agitation and digestion the resultant liquid containing precipitate was transferred to a container for observing settling in the manner comparable to the observations carried out in the preceding examples.

Example IV In accordance with this example, a preformed lanthanum fluoride precipitate was prepared. Approximately 86 ml. of solution of the type already described was treated with 3.7 ml. of concentrated hydrogen fluoride.

V in milliliters against settling time.

Approximately 10.32 ml. of the lead-lanthanum mixture as already described was added to the fluoride solution. This was added at about the rate of 0.5 ml. per 1% minute interval. In other words, this example was substantially the same as the preceeding example and was carried out for providing an approximate check of the preceeding example. The resultant liquid containing precipitate was digested for approximately 2 /2 hours after all the reagent had been added. It was then transferred to a container to observe the settling.

In all of the preceding examples, observations relative to settling were tabulated and plots made of this data which are reproduced on the attached drawings.

Referring to Fig. 1, there is graphically illustrated the curves resulting from the plotting the precipitate volume As there indicated, the control runs illustrated by curves 1 and 2 corresponding to Examples I and II, provide a basis of comparison. By reference to curves 3 and 4 corresponding to Examples III and IV in which an inorganic compound had been coprecipitated, it will be observed that the precipitate settled relatively rapidly. The foregoing data was derived from observing the settling of the liquids substantially immediately following digestion.

In order to observe the improvement from another aspect, the containers having the liquid and precipitate therein were shaken in order to cause the precipitate to be again dispersed throughout the liquid. Then the precipitates were again permitted to settle.

Referring to Fig. 2, the observed data again is plotted in a manner comparable to that already described. It may be observed that the resettling of precipitates prepared in accordance with the present invention, as exemplified by curves 3 and 4, were relatively more rapid than the settling rate exhibited by those conventional runs exemplified by curves 1 and 2.

A number of other runs similar to the foregoing were conducted in which the. quantities of reagent, order of addition and other similar conditions were varied somewhat.

From the various examples carried out it was determined that apparently the lead ion alone will cause some flocculation of a fluoride precipitate thereby improving its centrifuging and settling characteristics. However, this flocculation is more defined when the lead is precipitated as the sulfate. In addition, it appeared that lead sulfate will flocculate preformed lanthanum fluoride precipitates better than coformed precipitates. It also appeared that preferred operation would include the simultaneous precipitation of the inorganic material rather than precipitation after the fluoride precipitate has been formed. It appeared that either the source of lead ions or the sulfate ions may first be incorporated although, preferably in many instances, the sulfate ions and Ianthanum ions are added to a solution containing the lead and fluoride ions.

Varying the lead ion concentration from approximately 0.9 to 2 grams per liter appeared to give satisfactory results in all instances. In general, the smallest amount of lead ion addition consistent with the production of a precipitate of improved characteristics would be employed in order to avoid waste by using excesses. Also the smaller the amount present the more easily it may be eliminated in subsequent steps after it has served its purpose.

Inasmuch as fluoride precipitates containing Pu are in many instances to be further treated for separation and concentration of the Pu, additional examples were carried out for determining that the resultant precipitates might be redissolved and further processed.

Example V In accordance with this example, the material treated comprised nitric acid solution containing Pu which had been subjected to reduction by means of oxalic acid.

Approximately 1 liter of this solution was placed in a stainless steel container and rprerormed "lanthanum fluoride precipitate prepared thereinI Thafis, hydrogen flouride to make the solution 1 N'therei'n' and lead ions in a concentration of about 1.5 grams per liter were incorporated into the solution. There was also added a content of sulfuric acid sufficient to make solution approximately" 0.1 normal therein. A source of'lanthanum ions in a concentration of about 225 milligrams of La+ per liter were 'incorpor'ated. The process was conducted as already described so that the lead sulfate precipitated substantially "simultaneously with the lanthanum fluoride. The precipitate was digested for about 2 /2 hours and centrifuged. The centrifuged cakewas washed with 'wash' solution c mpnsingi M HF and 1 M The precipitate centrifuged very quickly and made a clean separation from the supernatant liquor." Theprecipit'atewas sliirri'ed in Water to 'a concentration of about 2.67 g'rams'of lanthanum ions per literf. Then potassium hydroxide was added to give a 15% solution thereof at a lanthanum concentration of about 2.05 grams per liter. The mixture was maintained at a temperature of about 75C. for one honrduring which the lanthanum fluoride containing Puwas" converted to lanthanum hydroxide. The lead remainedin solution in the potassium hydroxide. The lanthanum hydroxide precipitate containing Pu may then be dissolved in nitric acid and further treated in conventional manner. as by further fluoride precipitations and/orperoxide 'precipitations to concentrate the Pu or toobtain derivatives thereof.

The treatment of fluoride precipitates 'with KOH, .per se, is not a part of the present invention or a limitation thereon. The fluoride precipitates of tliefpresent invention may be dissolved by} otherprocedures, as for example, by the use of alkali carbonates;

From the foregoing it will be observed that We have provided a methodwhereby an improved fluoride type of carrier precipitate may be obtained by precipitating the fluoride precipitate in the presence of inorganic materials such as lead'sulfate. Preferably the precipitation is ac complished by adding sulfuric acid or other source of sulfate ions together with a solution containing a source of lanthanum ions, to a solution containing lead ions and fluoride ions. The concentration of lead ions (1%) would preferably be about 1 /2 grams per liter and the concentration of sulfate ions would be about 0.1 normal. However, these values are merely set forth as guides and the content of lead may vary between a trace and about 2 grams per liter. The lead maybe greater than 2 grams, but if an oxalic acid reduced solution'containing Pu is being treated some oxalate of lead may also. precipitate and this is not preferred. The content of sulfate ion would be suflicient, dependent upon the particular lead content, to precipitate the lead.. Preferably no large excesses of sulfate ions are present becauseof possible corrosion. The concentration ofthe other components such lanthanum and fluoride ions and the like may be in accordance with standard practice. Since these values are adequately described in copend ing applications such as 519,714 and other 'applications,.extended discussion thereof in this application is unnecessary.

In place of lead or supplementalthereto other materials which do not interfere with the carrying by the fluoride and which improve the characteristics of the precipitate maybe employed. For example, amphoteric metals which are alkali soluble and consequentlymay beelirninated in metathesis with KOH, are preferably employed. Exemplary of such other materials :are the various stannic compounds and compounds derived from aluminum, antimony and arsenic. t

In general, it has been found that the improved carrier precipitate in accordance with the present invention not only exhibits improved characteristics such as better settling and centrifuging properties, but that the recovery of product (Pu) is better. That is, the supernatant from separating product in accordance with the'present invention contained only A to /3 of the amount of Pu product diverted to the supernatant when compared with a control supernatant where a standard fluoride precipitation is accomplished. Presumably this may be due to the retention in the supernatant liquid from the standard process, of small amounts of fine precipitate. On the other hand, in accordance with the present invention substantially all of the precipitate separates out.

The invention has been described as applied to the fluoride type of precipitate, illustrated by lanthanum fluoride since this constitutes the preferred embodiment as well as a type of precipitate frequently encountered in plant processes, but our invention is not limited specifically thereto. Similar procedure may be applied in the formation of other fluoride precipitates exemplified by the formation of potassium plutonium fluoride and the like. That is, in certain other instances fluoride precipitates which do not flocculate or otherwise present difliculties of formation and separation may be improved by the application of the principles of our invention. In general, after the precipitate has been formed in accordance with the procedure of the present invention, the solution containing precipitate may be further treated in accordance with conventional procedure for restoring the condition of the materials to their usual character as of that point in any particular process.

The process may be applied to solutions containing Pu from tracer amounts to several hundred grams thereof. Also large volumes of liquids may be treated. On larger scale the concentration of La+ ion may be from about to 225 mg. per liter supplied in several separate additions if desired. The concentration of HF may be within the range of about 0.2 to l'M or higher. However, my invention is not limited in these respects as the concentration of the reagents suggested are merely guides to preferred practice.

It is to be understood that all matter contained in the above description and examples shall be interpreted as illustrative and not limitative of the scope of this invention, and it is intended to claim the present invention as broadly as possible in view of the prior art.

We claim:

1. In a process for the recovery of plutonium values from an acidic solution containing the same comprising adding components which will by interaction produce a carrier precipitate, the method for improving the operation which comprises precipitating in said solution, contemporaneously with the production of said carrier precipitate, a lead compound, in amount sufficient to improve the separation characteristics of the carrier precipitate.

2. In a process for the recovery of plutonium values from an aqueous, acidic solution containing the same by means of carrier precipitation involving precipitating 11 said solution a carrier comprising a fluoride compound, the method for improving the carrier precipitat on operation which comprises coprecipitating lead fluoride with said carrier.

3. In a process for the recovery of plutonium values from an aqueous, acidic solution containing the same by means of carrier precipitation involving precipitating in said solution a carrier comprising a fluoride compound, the method for improving the carrier precipitation operation which comprises co-precipitating lead sulfate with the carrier.

4. In a process for the recovery of plutonium values from an aqueous, acidic solution containing the same by means of carrier precipitation involving the precipitation in said solution of lanthanum fluoride as the carrier, the method for improving the carrier precipitation operation which comprises co-precipitating lead sulfate'with the carrier. 1

5. In a process for the recovery of plutonium values from an aqueous, acidic nitric acid solution containing the same by means of carrier precipitation involving the precipitation in said solution of lanthanum fluoride as the carrier, the method for improving the carrier precipitation operation which comprises adding to the solution a soluble lead compound and sulfuric acid, contemporaneously with the precipitation of the carrier and in amounts sufficient to improve the separation characteristics of the carrier precipitate.

6. In a process for the recovery of plutonium values from an aqueous, acidic solution containing the same by means of a carrier precipitation operation involving the precipitation in said solution of lanthanum fluoride as the carrier, the method for improving the carrier precipitation operation which comprises co-precipitating from the said solution lead sulfate with the carrier, then separating from thusly formed'co-precipitate from its supernatant solution, and thereafter leaching the thereby separated co-precipitate with potassium hydroxide to remove lead contained therein.

7. In a process for the separation of plutonium values from fission products, both contained in a common aqueous nitric acid solution, by means of carrier precipitation of the plutonium from the said solution involving the precipitation in said solution of lanthanum fluoride as the carrier, the method for improving the carrier precipitation operation which comprises adding to the solution a soluble lead compound and sulfuric acid, contemporaneously with the precipitation of the carrier and in amounts sufiicient to improve the separation characteristics of the carrier precipitate,

8. In a carrier precipitation process involving the precipitation in an aqueous, acidic solution of a carrier comprising a fluoride compound, the method for improving the separation characteristics of the carrier precipitate which comprises co-precipitating therewith lead sulfate.

9. In the precipitation of lanthanum fluoride in an aqueous acidic solution, the method for improving the separation characteristics of the lanthanum fluoride precipitate which comprises co-precipitating lead fluoride with said lanthanum fluoride precipitate.

10. In a process for removing a material from an aqueous, nitric acid solution by a carrier precipitation operation involving the precipitation of lanthanum fluoride as the carrier in the said solution, the method for improving the precipitation characteristics of the carrier precipitate which comprises co-precipitating lead sulfate with the lanthanum fluoride carrier precipitate.

11. In a process for the recovery of fission products from an aqueous nitric acid solution containing the same by means of a carrier precipitation operation involving the precipitation in said solution of lanthanum fluoride as the carrier, the method for improving the carrier precipitation operation which comprises adding to the said solution a soluble lead compound and sulfuric acid, contemporaneously with the precipitation of the carrier and in amounts sufficient to improve the separation characteristics of the carrier precipitate.

References Cited in the file of this patent UNITED STATES PATENTS 2,785,951 Thompson et a1. Mar. 19, 1957 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION" Patent No. 2,863,719 December 9, 1958 Harry Jo Kamack a1.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 22, for "pecipitated" read. m1 precipitated column 3, line 34, for "out" read our column 5, line 22, before "about" insert was column 9, line 1'7, for "from", first occurrence, read an the Signed and sealed this 9th day of June 1959,

(SEAL) Attest:

KARL Ha AXLINE ROBERT C. WATSON Commissioner of Patents Attesting Officer UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,863,719 December 9, 1958 Harry J Kamack et 211.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 22', for "pecipitated" read. me precipitated 3 column 3, line 34, for "out" read our column 5, line 22, before "about" insert was column 9, line 17, for "from", first occurrence, read the a Signed and sealed this 9th day of June 1959,

(SEAL) Attest:

KARL H INE Attesting Oificer ROBERT C. WATSON Commissioner of Patents 

1. IN A PROCESS FOR THE RECOVERY OF PLUTONIUM VALUES FROM AN ACIDIC SOLUTION THE SAME COMPRISING ADDING COMPONENTS WHICH WILL BY INTERACTION PRODUCE A CARRIER PRECIPITATE, THE METHOD FOR IMPROVING THE OPERATION WHICH COMPRISES PRECIPITATING IN SAID SOLUTION, CONTEMPORANEOUSLY WITH AN PRODUCTION OF SAID CARRIER PRECIPITATE, A LEAD COMPOUND, IN AMOUNT SUFFICIENT TO IMPROVE THE SEPARATION CHARACETERISTICS OF THE CARRIER PRECIPITATE. 